I. Field of the Invention
The present invention relates generally to kitchen appliances, and more particularly to a machine for automatically preparing any one of yogurt, soft frozen yogurt, hard frozen yogurt and cheese, at home.
II. Discussion of the Prior Art
Because of its taste and nutritional value, yogurt has been an increasingly popular food product. Many brand name yogurt products are available to the consumer in supermarkets. Traditionally, and because of the expense of these products, some consumers attempt to make yogurt at home. Warming devices for making yogurt at home are available and are discussed in the prior art. For example, U.S. Pat. No. 4,009,368 to Faivre et al. describes an electrically heated yogurt-making machine having an enclosure containing a receptacle into which boiled milk and a yogurt starter is placed. The enclosure contains an electrical heating element and a fusible material (wax) which is adapted to be heated to a melting point by the heating element. Heat from the melted wax is transferred to the milk container. The purpose of the wax is to provide a thermal mass exhibiting a temperature plateau at or near the optimum for incubating the bacteria used to transform the milk to yogurt.
The yogurt making process requires that the yogurt mix incubate relatively undisturbed for a somewhat unpredictable number of hours until the desired consistency and acidity is achieved. More frequent disturbance results in curdling of the milk product and the formation of cheese. If too high a temperature is employed, it accelerates the process to the point where it is difficult to catch the end-point where consistency and flavor are at their optimum. Traditional, home-based, room temperature yogurt techniques are slow, sometimes taking as long as 12 hours. The room temperature yogurt process does, however, offer the advantage of allowing it to be checked at reasonable intervals so that the incubation process might be terminated at or near its optimal point by initiating cooling. The incubation process can be accelerated to only about four hours by providing a warm environment for the yogurt mix, but if the optimal point is not detected accurately, the yogurt becomes more acidic and less palatable. Thus, considerable operator attention and care is required with prior art warming apparatuses.
The yogurt making appliances of the present invention obviate these problems. Specifically, the yogurt making machines of the present invention require no operator intervention or monitoring during the reasonably rapid, heating, cooling and warmed incubation process. The warming is automatically stopped at the desired point in the process with refrigeration being initiated automatically to terminate further incubation.
A further object and advantage of the present invention is that the same machine can be used to facilitate the preparation of frozen yogurt and ice cream as well as both cultured and artificially curdled cheese products.